Modern motor vehicles employ numerous types of sensors and sensor assemblies throughout the vehicle which are used in control systems for powertrain, chassis, interior cabin environment, and safety, among many other applications. One type of sensor is used for detecting the ride height position of the vehicle. This is a measure of the position of sprung chassis or body components relative to unsprung chassis components such as axles, steering knuckles, and axle hubs (also referred to as jounce motion).
Such sensors are used in a variety of applications. For example, some vehicles have headlights systems which adapt to various loading conditions to maintain their desired aiming point over a variety of vehicle loads. In such applications, a ride height sensor indicating the position of a front and rear wheel component is processed to set the aiming point. Another application is for actively controlled suspension components such as shock absorbers and springs which are dynamically adjusted based on wheel motion inputs. Adjustments of spring preloading for rear axles is also accomplished using data from a ride height sensor used to inflate air bladders or other suspension components to adapt to different loading conditions.
Many designs of ride height sensors are presently known. The devices currently available operate generally satisfactorily. However, there are certain failure modes and performance requirements challenges with current designs. Since these devices are located in the undercarriage area of a motor vehicle, they are exposed to a very hostile environment of moisture, salt, dirt, physical damage, and extreme temperature changes.
One goal is to reduce the leakage paths present in the sensor assembly which can allow moisture to enter sensitive electronic elements of the sensor. Many current designs of such sensors have at least two leakage paths. One of these paths is related to a cover or potting material placed over installed electronic components. This leakage path is prone to failure and sealing it imposes cost penalties. Irrespective of the design of the sensor assembly, there is a continuing desire by automotive manufacturers to reduce the mass and cost of all automotive components, including chassis sensors.
Another goal is to reduce the complexity of and improve the components of the sensor assembly including, for example, the sensor cartridge.